JP2013169859A - Control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a method of learning responsiveness of an air-fuel ratio sensor and to provide a relatively large number of opportunities to learn the responsiveness.SOLUTION: When an engine is cranked (S100), a maximum slope value ΔVafmax based on a slope value ΔVaf of an output voltage of an air-fuel ratio sensor is set (S150 to S170), a normalized maximum slope value ΔVafmaxno is set by normalizing the set maximum slope value ΔVafmax (S190), and a learned value ΔVafmaxlv of responsiveness of the air-fuel ratio sensor is calculated (S200) by using the set normalized maximum slope value ΔVafmaxno.

Description

  The present invention relates to a control device for a hybrid vehicle.

  Conventionally, this type of hybrid vehicle control apparatus performs engine air-fuel ratio feedback control based on the output value of an air-fuel ratio sensor. When a predetermined time elapses after the engine is temporarily stopped, the air-fuel ratio feedback control is performed. When the output value of the fuel ratio sensor is in a lean region, an engine that detects an abnormal response delay of the air fuel ratio sensor and disallows intermittent operation of the engine has been proposed (for example, see Patent Document 1). In this hybrid vehicle, the deterioration of exhaust emission at the time of restart is suppressed by such control.

JP 2008-143482 A

  In the hybrid vehicle control apparatus described above, when the engine operation is stopped before the predetermined time has elapsed since the engine restart, it is determined whether or not the air-fuel ratio sensor has a response delay abnormality. Can not. Further, the above-described hybrid vehicle control device only detects an abnormality in the response delay of the air-fuel ratio sensor, and does not grasp (learn) the responsiveness itself. Therefore, it is considered as one of the problems to construct a method for learning the responsiveness of the air-fuel ratio sensor and to make the learning possible at relatively many opportunities.

  The main purpose of the hybrid vehicle of the present invention is to construct a learning method for the responsiveness of the air-fuel ratio sensor and to enable the learning to be performed on a relatively large number of occasions.

  The control device for a hybrid vehicle of the present invention employs the following means in order to achieve the main object described above.

The control device for a hybrid vehicle of the present invention includes:
An engine; a motor capable of cranking the engine; a battery capable of supplying electric power to the motor; and an air-fuel ratio sensor attached to an exhaust system of the engine and having an output value that varies depending on the air-fuel ratio. A control device for a hybrid vehicle,
Learning the responsiveness of the air-fuel ratio sensor using the slope of the output value of the air-fuel ratio sensor during cranking of the engine by the motor.
It is characterized by that.

  In this hybrid vehicle control device, the response of the air-fuel ratio sensor is learned by using the gradient of the output value of the air-fuel ratio sensor when the engine is cranked by the motor. Normally, when the engine is cranked, new air (fresh air) is introduced into the intake pipe, so the air-fuel ratio changes to the lean side. The output value of the air-fuel ratio sensor changes according to the change in the air-fuel ratio. Therefore, the responsiveness of the air-fuel ratio sensor can be learned by using the slope of the output value of the air-fuel ratio sensor at the time of engine cranking. In hybrid vehicles, the engine runs intermittently from system startup to system shutdown, so the responsiveness of the air-fuel ratio sensor is learned using the slope of the output value of the air-fuel ratio sensor during engine cranking. Thus, it is considered that learning can be performed at more opportunities as compared to learning after a predetermined time has elapsed after engine startup. Here, the “air-fuel ratio sensor” may be a sensor whose output value increases substantially linearly as the air-fuel ratio increases.

In such a hybrid vehicle control device of the present invention,
The cranking maximum slope value, which is the maximum value of the slope of the output value of the air-fuel ratio sensor at the time of cranking of the engine, is the output value of the air-fuel ratio sensor at the start of cranking of the engine, atmospheric pressure, throttle opening It is also possible to normalize using at least one of the degrees and calculate the learning value of the responsiveness of the air-fuel ratio sensor using the maximum cranking gradient value after the normalization. Here, “normalization” means that the cranking maximum slope value is converted into the cranking maximum slope value when the output value of the air-fuel ratio sensor at the start of cranking of the engine is a predetermined air-fuel ratio, or atmospheric pressure Can be converted into a cranking maximum slope value when the pressure is a predetermined pressure, or can be converted into a cranking maximum slope value when the throttle opening is a predetermined opening.

  In the hybrid vehicle control apparatus that calculates the learning value of the responsiveness of the air-fuel ratio sensor using the normalized cranking maximum slope value, the calculated cranking maximum slope value after normalization is calculated. A sum of a value obtained by multiplying a reflection coefficient larger than 0 and smaller than 1 and a value obtained by multiplying the previous learned value of the response of the air-fuel ratio sensor by a value obtained by subtracting the reflection coefficient from value 1 is the air-fuel ratio sensor. It is also possible to calculate as a learning value of the responsiveness. Here, as the “reflection coefficient”, a value larger than 0 and smaller than 1 can be used.

  In the hybrid vehicle control apparatus of the present invention, when the output of the motor is limited to less than a threshold value or when the rise of the engine speed during cranking of the engine is slower than the threshold value, the response of the air-fuel ratio sensor It can be assumed that sex learning is not performed.

  Furthermore, in the hybrid vehicle control device of the present invention, after the engine is started, the timing for starting the air-fuel ratio feedback control is set so as to be delayed as the responsiveness of the air-fuel ratio sensor is low. You can also. In the hybrid vehicle control device according to this aspect, after a predetermined time has elapsed since the start of the engine, the output value of the air-fuel ratio sensor is richer than the target air-fuel ratio, and the responsiveness of the air-fuel ratio sensor is high. The air-fuel ratio feedback control may be started when the threshold value is set so as to approach the target air-fuel ratio as the value decreases or when the theoretical air-fuel ratio side is reached from the threshold value.

  Alternatively, in the hybrid vehicle control device of the present invention, the limit value of the integral term in the air-fuel ratio feedback control may be set so as to decrease as the responsiveness of the air-fuel ratio sensor decreases.

1 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 20 as an embodiment of the present invention. 2 is a configuration diagram showing an outline of the configuration of an engine 22. FIG. It is explanatory drawing which shows an example of the output characteristic of the air fuel ratio sensor 135a and the oxygen sensor 135b. It is explanatory drawing which shows an example of the relationship between battery temperature Tb and the basic value of input / output restrictions Win and Wout. It is explanatory drawing which shows an example of the relationship between the electrical storage ratio SOC of the battery 50, the output restriction correction coefficient, and the input restriction correction coefficient. It is a flowchart which shows an example of the air-fuel ratio sensor responsiveness learning routine performed by engine ECU24 of an Example. It is explanatory drawing which shows an example of the relationship line which shows the relationship between the voltage Vaf0 at the time of start, and maximum inclination value (DELTA) Vafmax. It is explanatory drawing which shows the mode of the time change of the rotation speed Ne of the engine 22, the intake air amount Qa, the output voltage Vaf of the air-fuel ratio sensor 135a, and the inclination value ΔVaf when the engine 22 is cranked and started by the motor MG1. 5 is a flowchart showing an example of an air-fuel ratio F / B control start permission routine executed by an engine ECU 24. It is explanatory drawing which shows an example of the map for a start air fuel ratio setting. It is explanatory drawing which shows an example of the time change state of the rotation speed Ne of the engine 22, the output voltage Vaf of the air fuel ratio sensor 135a, the air fuel ratio feedback correction amount ΔQf, and the presence or absence of execution of the air fuel ratio feedback control. It is a flowchart which shows an example of the air-fuel ratio sensor responsiveness learning routine of a modification. It is a flowchart which shows an example of the air-fuel ratio sensor responsiveness learning routine of a modification. It is explanatory drawing which shows an example of the relationship line which shows the relationship between atmospheric pressure Pa and maximum inclination value (DELTA) Vafmax. It is explanatory drawing which shows an example of the relationship line which shows the relationship between throttle opening TH and maximum inclination value (DELTA) Vafmax. It is explanatory drawing which shows an example of the map for integral term limit value setting. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 120 according to a modification. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 220 of a modified example. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 320 of a modified example. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 420 according to a modification.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. As shown in the drawing, the hybrid vehicle 20 of the embodiment includes an engine 22 that outputs power using gasoline or light oil as a fuel, an engine electronic control unit (hereinafter referred to as an engine ECU) 24 that controls the drive of the engine 22, an engine, and the like. A planetary gear 30 having a carrier connected to the crankshaft 26 and a ring gear connected to a drive shaft 36 connected to drive wheels 38a and 38b via a differential gear 37, and a rotor configured as a synchronous generator motor, for example. Motor MG1 connected to the sun gear of planetary gear 30, for example, a motor MG2 configured as a synchronous generator motor and having a rotor connected to drive shaft 36, inverters 41 and 42 for driving motors MG1 and MG2, Inverters 41 and 42 not shown A motor electronic control unit (hereinafter referred to as a motor ECU) 40 that drives and controls the motors MG1 and MG2 by switching the elements, and a motor MG1, configured as, for example, a lithium ion secondary battery via inverters 41 and 42. A battery 50 that exchanges power with the MG 2, a battery electronic control unit (hereinafter referred to as a battery ECU) 52 that manages the battery 50, and a hybrid electronic control unit (hereinafter referred to as a HVECU) 70 that controls the entire vehicle. Prepare.

  The engine 22 is configured as an internal combustion engine capable of outputting power using a hydrocarbon-based fuel such as gasoline or light oil, and the air purified by an air cleaner 122 is passed through a throttle valve 124 as shown in FIG. Inhalation and gasoline are injected from the fuel injection valve 126 to mix the sucked air and gasoline, and this mixture is sucked into the combustion chamber through the intake valve 128 and explosively burned by an electric spark from the spark plug 130. Thus, the reciprocating motion of the piston 132 pushed down by the energy is converted into the rotational motion of the crankshaft 26. Exhaust gas from the engine 22 is sent to the outside air through a purification device 134 having a purification catalyst (three-way catalyst) 134a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). Discharged. The three-way catalyst 134a stores oxygen from the exhaust when the exhaust from the engine 22 is lean with respect to the stoichiometric air-fuel ratio, and stores the oxygen when the exhaust from the engine 22 is rich with respect to the stoichiometric air-fuel ratio. Released into the exhaust. An air-fuel ratio sensor 135a in which an output value (output voltage Vaf) changes approximately linearly according to the air-fuel ratio is provided upstream of the purification device 134 in the exhaust pipe of the engine 22, and downstream of the purification device 134. Is provided with an oxygen sensor 135b whose output value (output voltage Vo) changes rapidly depending on whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio. FIG. 3 shows an example of output characteristics of the air-fuel ratio sensor 135a and the oxygen sensor 135b. In the example of FIG. 3, the air-fuel ratio sensor 135a increases the output voltage Vaf substantially linearly as the air-fuel ratio increases, and the oxygen sensor 135b compares the output value Vo when the air-fuel ratio is richer than the stoichiometric air-fuel ratio. The output value Vo becomes relatively small at the lean side.

  The engine ECU 24 is configured as a microprocessor centered on the CPU 24a. In addition to the CPU 24a, the engine ECU 24 includes a ROM 24b for storing processing programs, a RAM 24c for temporarily storing data, an input / output port and a communication port (not shown). Prepare. The engine ECU 24 receives signals from various sensors that detect the state of the engine 22, for example, a crank position from the crank position sensor 140 that detects the rotational position of the crankshaft 26, and a water temperature that detects the temperature of cooling water in the engine 22. A cooling water temperature Tw from the sensor 142, an in-cylinder pressure Pin from a pressure sensor (not shown) attached in the combustion chamber, a cam for detecting the intake valve 128 for intake and exhaust to the combustion chamber and the rotational position of the camshaft for opening and closing the exhaust valve The cam position from the position sensor 144, the throttle opening TH from the throttle valve position sensor 146 for detecting the position of the throttle valve 124, the intake air amount Qa from the air flow meter 148 attached to the intake pipe, and also attached to the intake pipe. Temperature The intake air temperature Tin from the heater 149, the catalyst temperature Tc from the temperature sensor 134b for detecting the temperature of the purification catalyst 134a, the output voltage Vaf from the air-fuel ratio sensor 135a attached to the exhaust pipe, and the oxygen sensor also attached to the exhaust pipe The output voltage Vo etc. from 135b is input via the input port. The engine ECU 24 also integrates various control signals for driving the engine 22, such as a drive signal to the fuel injection valve 126, a drive signal to the throttle motor 136 that adjusts the position of the throttle valve 124, and an igniter. The control signal to the ignition coil 138 and the control signal to the variable valve timing mechanism 150 that can change the opening / closing timing of the intake valve 128 are output via the output port. The engine ECU 24 communicates with the HVECU 70, controls the operation of the engine 22 by a control signal from the HVECU 70, and outputs data related to the operating state of the engine 22 as necessary. The engine ECU 24 also calculates the rotational speed of the crankshaft 26, that is, the rotational speed Ne of the engine 22 based on the crank position from the crank position sensor 140.

  Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The motor ECU 40 receives signals necessary for driving and controlling the motors MG1 and MG2, for example, rotational positions θm1 and θm2 from rotational position detection sensors 43 and 44 that detect the rotational positions of the rotors of the motors MG1 and MG2, and not shown. A phase current applied to the motors MG1 and MG2 detected by the current sensor is input via the input port, and the motor ECU 40 outputs a switching control signal to switching elements (not shown) of the inverters 41 and 42. It is output through the port. The motor ECU 40 is in communication with the HVECU 70, controls the driving of the motors MG1 and MG2 by a control signal from the HVECU 70, and outputs data related to the operating state of the motors MG1 and MG2 to the HVECU 70 as necessary. The motor ECU 40 also calculates the rotational angular velocities ωm1, ωm2 and the rotational speeds Nm1, Nm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2 from the rotational position detection sensors 43, 44. ing.

  Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The battery ECU 52 receives signals necessary for managing the battery 50, for example, an inter-terminal voltage Vb from a voltage sensor (not shown) installed between the terminals of the battery 50 and a power line connected to the output terminal of the battery 50. The charging / discharging current Ib from the attached current sensor (not shown), the battery temperature Tb from the temperature sensor 51 attached to the battery 50, and the like are input, and data regarding the state of the battery 50 is communicated to the HVECU 70 as necessary. Send. Further, in order to manage the battery 50, the battery ECU 52 is a power storage that is a ratio of the capacity of the electric power that can be discharged from the battery 50 at that time based on the integrated value of the charge / discharge current Ib detected by the current sensor. The ratio SOC is calculated, and the input / output limits Win and Wout, which are the maximum allowable power that may charge / discharge the battery 50, are calculated based on the calculated storage ratio SOC and the battery temperature Tb. The input / output limits Win and Wout of the battery 50 are set to the basic values of the input / output limits Win and Wout based on the battery temperature Tb, and the output limiting correction coefficient and the input limiting limit are set based on the storage ratio SOC of the battery 50. It can be set by setting a correction coefficient and multiplying the basic value of the set input / output limits Win and Wout by the correction coefficient. FIG. 4 shows an example of the relationship between the battery temperature Tb and the basic values of the input / output limits Win and Wout, and FIG. 5 shows an example of the relationship between the storage ratio SOC of the battery 50, the output limiting correction coefficient, and the input limiting correction coefficient. Indicates. The input limit Win set in this manner is more limited as the battery temperature Tb is lower in a region where the battery temperature Tb is lower than a predetermined temperature Tblo (for example, 0 ° C., 5 ° C., 10 ° C., etc.). In the region where the battery temperature Tb is higher than a predetermined temperature Tbhi (for example, 45 ° C., 50 ° C., 55 ° C., etc.), the battery temperature Tb is greatly limited, and the storage rate SOC is set to a predetermined value Shi (for example, 55% 60%, 65%, etc.), the larger the power storage rate SOC, the larger the limit. Further, the output limit Wout is greatly restricted as the battery temperature Tb is lower in a region where the battery temperature Tb is lower than the predetermined temperature Tblo, and is greatly restricted as the battery temperature Tb is higher in a region where the battery temperature Tb is higher than the predetermined temperature Tbhi. In a region where the power storage rate SOC is lower than a predetermined value Slo (for example, 35%, 40%, 45%, etc.), the power storage rate SOC is more greatly limited.

  Although not shown, the HVECU 70 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. The HVECU 70 includes an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the operation position of the shift lever 81, and an accelerator opening degree from the accelerator pedal position sensor 84 that detects the amount of depression of the accelerator pedal 83. Acc, the brake pedal position BP from the brake pedal position sensor 86 that detects the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 88, the atmospheric pressure Pa from the atmospheric pressure sensor 89, and the like are input via the input port. Yes. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, and the battery ECU 52.

  In the hybrid vehicle 20 of the embodiment thus configured, the required torque Tr * to be output to the drive shaft 36 is calculated based on the accelerator opening Acc and the vehicle speed V corresponding to the depression amount of the accelerator pedal by the driver. The operation of the engine 22, the motor MG1, and the motor MG2 is controlled so that the required power corresponding to the required torque Tr * is output to the drive shaft 36. As the operation control of the engine 22, the motor MG1, and the motor MG2, the operation of the engine 22 is controlled so that the power corresponding to the required power is output from the engine 22, and all the power output from the engine 22 is transmitted to the planetary gear 30 and the motor. The torque conversion operation mode in which the motor MG1 and the motor MG2 are driven and controlled so that the torque is converted by the MG1 and the motor MG2 and output to the drive shaft 36, and the sum of the required power and the power required for charging and discharging the battery 50 is met. Operation of the engine 22 is controlled so that power is output from the engine 22, and all or part of the power output from the engine 22 with charge / discharge of the battery 50 is torque generated by the planetary gear 30, the motor MG1, and the motor MG2. The required power is output to the drive shaft 36 with conversion. Charge-discharge drive mode for driving and controlling the motors MG1 and MG2, there is a motor operation mode in which operation control to output a power commensurate to stop the operation of the engine 22 to the required power from the motor MG2 to the drive shaft 36. The torque conversion operation mode and the charge / discharge operation mode are modes in which the engine 22, the motor MG1, and the motor MG2 are controlled so that the required power is output to the drive shaft 36 with the operation of the engine 22. Since there is no substantial difference in control, both are hereinafter referred to as the engine operation mode.

  In the engine operation mode, the HVECU 70 sets the required torque Tr * to be output to the drive shaft 36 based on the accelerator opening Acc from the accelerator pedal position sensor 84 and the vehicle speed V from the vehicle speed sensor 88, and the set required torque Multiply Tr * by the rotational speed Nr of the drive shaft 36 (for example, the rotational speed Nm2 of the motor MG2 or the rotational speed obtained by multiplying the vehicle speed V by the conversion factor) to calculate the traveling power Pdrv * required for traveling, The required power Pe * as the power to be output from the engine 22 is set by subtracting the charge / discharge required power Pb * (a positive value when discharging from the battery 50) from the calculated traveling power Pdrv *. Then, the target rotational speed Ne of the engine 22 is obtained using an operation line (for example, a fuel efficiency optimal operation line) as a relationship between the rotational speed Ne of the engine 22 and the torque Te that can efficiently output the required power Pe * from the engine 22. * And the target torque Te * are set, and the motor is controlled by the rotational speed feedback control so that the rotational speed Ne of the engine 22 becomes the target rotational speed Ne * within the range of the input / output limits Win and Wout of the battery 50. A torque command Tm1 * as a torque to be output from MG1 is set, and when the motor MG1 is driven by the torque command Tm1 *, the torque acting on the drive shaft 36 via the planetary gear 30 is subtracted from the required torque Tr * to reduce the motor MG2. Torque command Tm2 * is set, and the target rotational speed Ne * and target torque Te * are set. In its sent to the engine ECU 24, the torque command Tm1 *, the Tm2 * is sent to the motor ECU 40. The engine ECU 24 that has received the target rotational speed Ne * and the target torque Te *, controls the intake air amount, fuel injection control, and ignition of the engine 22 so that the engine 22 is operated by the target rotational speed Ne * and the target torque Te *. The motor ECU 40 that performs control or the like and receives the torque commands Tm1 * and Tm2 * performs switching control of the switching elements of the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1 * and Tm2 *. By such control, it is possible to travel while outputting the required torque Tr * to the drive shaft 36 within the range of the input / output limits Win and Wout of the battery 50 while operating the engine 22 efficiently. In this engine operation mode, when the required power Pe * of the engine 22 reaches a stop threshold value Pstop defined as the upper limit of the range of the required power Pe * that is better to stop the engine 22, the engine 22 It is determined that the stop condition is satisfied, the operation of the engine 22 is stopped, and the motor operation mode is shifted to.

  Here, the fuel injection control of the engine 22 will be described. In the fuel injection control, first, based on the intake air amount Qa from the air flow meter 148, a basic fuel injection amount Qftmp for setting the air-fuel ratio to the target air-fuel ratio AF * (for example, the theoretical air-fuel ratio) is set, and the air-fuel ratio sensor 135a The air-fuel ratio feedback correction amount ΔQf is set by the following equation (1) so that the air-fuel ratio corresponding to the output voltage Vaf (hereinafter referred to as detected air-fuel ratio AFdet) becomes the target air-fuel ratio AF *, and the set air-fuel ratio feedback correction amount is set. The target fuel injection amount Qf * is set by adding ΔQf to the basic fuel injection amount Qftmp, and the fuel injection valve 126 is controlled using the set target fuel injection amount Qf *. Here, Expression (1) is a relational expression in feedback control (air-fuel ratio feedback control) for causing the detected air-fuel ratio AFdet to become the target air-fuel ratio AF *. In Expression (1), “k1” is The gain of the proportional term, and “k2” is the gain of the integral term. When the air-fuel ratio feedback control is not executed such as immediately after the start of the engine 22, the target fuel injection amount Qf * is set as the basic fuel injection amount Qftmp, and the fuel injection valve 126 is set using the set target fuel injection amount Qf *. Control.

  ΔQf = k1 ・ (AF * -AFdet) + k2 ・ ∫ (AF * -AFdet) dt (1)

  In the motor operation mode, the HVECU 70 sets a required torque Tr * to be output to the drive shaft 36 based on the accelerator opening Acc and the vehicle speed V, sets a value 0 to the torque command Tm1 * of the motor MG1, and sets the battery 50. The torque command Tm2 * of the motor MG2 is set and transmitted to the motor ECU 40 so that the required torque Tr * is output to the drive shaft 36 within the range of the input / output limits Win, Wout. Then, the motor ECU 40 that receives the torque commands Tm1 * and Tm2 * performs switching control of the switching elements of the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1 * and Tm2 *. With such control, the engine 22 can travel by outputting the required torque Tr * to the drive shaft 36 within the range of the input / output limits Win and Wout of the battery 50 with the engine 22 stopped. In this motor operation mode, the required power Pe * of the engine 22 obtained by subtracting the charge / discharge required power Pb * of the battery 50 from the traveling power Pdrv * obtained by multiplying the required torque Tr * by the rotational speed Nr of the drive shaft 36. When the engine 22 has reached the starting threshold value Pstart defined as the lower limit of the range of the required power Pe *, it is determined that the engine 22 has been started, and the engine 22 is started. Then, it shifts to the engine operation mode.

  The engine 22 is started by outputting a cranking torque Tc for cranking the engine 22 from the motor MG1 within the range of the input / output limits Win and Wout of the battery 50, and outputting the torque to the drive shaft 36. The engine 22 is cranked by outputting torque for canceling the acting torque from the motor MG2, and when the rotational speed Ne of the engine 22 reaches a predetermined rotational speed Nest (for example, 1000 rpm), fuel injection control and ignition control It is done by starting. During the start of the engine 22, the drive control of the motor MG2 is performed so that the required torque Tr * is output to the drive shaft 36. That is, the torque to be output from the motor MG2 is the sum of the required torque Tr * and the torque for canceling the torque acting on the drive shaft 36 when the engine 22 is cranked by the motor MG1. Further, when cranking the engine 22 by the motor MG1, in the embodiment, the engine 22 is controlled so that the throttle opening TH becomes the idle target opening THid * as the throttle opening TH when the idle operation is performed. To do.

  Further, in the hybrid vehicle 20 of the embodiment, when the engine 22 is idled, the engine 22 has a basic opening THtmp that is predetermined so that the rotational speed Ne of the engine 22 becomes the idle rotational speed Nidl. Correction is made so that the difference between the rotational speed Ne and the idle rotational speed Nidl is canceled out, the target opening for idling THid * is set, and the engine 22 is controlled using the set target opening for idling THid *. The target opening degree THid * is learned.

  Next, the operation of the hybrid vehicle 20 of the embodiment thus configured, particularly the operation when learning the responsiveness of the air-fuel ratio sensor 135a will be described. FIG. 6 is a flowchart illustrating an example of an air-fuel ratio sensor responsiveness learning routine executed by the engine ECU 24 of the embodiment. This routine is executed repeatedly.

  When the air-fuel ratio sensor responsiveness learning routine is executed, the CPU 24a of the engine ECU 24 first determines whether or not the start condition of the engine 22 has been established since it has not been established (step S100). When it is determined that the start condition is not satisfied from the failure, this routine is terminated. Here, as the time when the start condition of the engine 22 is not satisfied, it can be considered that the required power Pe * is equal to or higher than the start threshold value Pstart during traveling in the motor operation mode. The process in step S100 is a process for determining whether or not cranking of the engine 22 by the motor MG1 is started.

  If it is determined in step S100 that the start condition of the engine 22 has not been satisfied, it is determined whether or not a learning condition for the responsiveness of the air-fuel ratio sensor 135a is satisfied (step S110). When it is determined that the condition is not satisfied, this routine is terminated. Here, the learning condition is, for example, a time condition in which a predetermined time (for example, 1 second or 2 seconds) has elapsed after the engine 22 is stopped, or an output voltage Vaf of the air-fuel ratio sensor 135a is less than the predetermined voltage Vafref. Certain voltage conditions can be used. Here, as the predetermined voltage Vafref, a voltage corresponding to a predetermined air-fuel ratio (for example, value 17 or value 18) larger than the theoretical air-fuel ratio (value 14.6) is used. In the embodiment, when at least one of the time condition and the voltage condition is not satisfied, it is determined that the learning condition is not satisfied, and when all of these are satisfied, it is determined that the learning condition is satisfied. did.

  When it is determined in step S110 that the learning condition is satisfied, the output voltage Vaf of the air-fuel ratio sensor 135a is input and set to the starting voltage Vaf0 as the output voltage Vaf at the start of cranking of the engine 22. Along with (steps S120 and S130), the slope value ΔVaf as a change amount per unit time (for example, 50 msec, 60 msec, 70 msec, etc.) of the output voltage Vaf, the maximum slope value ΔVafmax, the maximum slope as the maximum value of the slope value ΔVaf A value 0 as an initial value is set to each of the normalized maximum slope value ΔVafmaxlv as a value obtained by normalizing the value ΔVafmax (step S140).

  Subsequently, the slope value ΔVaf is inputted (step S150), and the inputted slope value ΔVaf is compared with the maximum slope value ΔVafmax (step S160). When the slope value ΔVaf is larger than the maximum slope value ΔVafmax, the slope value ΔVaf is maximized. The slope value ΔVafmax is set, that is, the maximum slope value ΔVafmax is updated (step S170). When the slope value ΔVaf is equal to or less than the maximum slope value ΔVafmax, the process of step S170 is not executed. Here, as the slope value ΔVaf, a value obtained by subtracting the output voltage Vaf that is a unit time earlier from the current output voltage Vaf of the air-fuel ratio sensor 135a by a slope value calculation routine (not shown) executed by the engine ECU 24 is input. did.

  Then, it is determined whether or not the engine 22 has been started (whether or not the cranking of the engine 22 has been completed) (step S180), and the engine 22 has not been started (the cranking of the engine 22 has been completed). If not, the process returns to step S150. Note that whether or not the engine 22 has been started can be determined, for example, based on whether or not the engine 22 has completely exploded.

  In this way, the processes of steps S150 to S180 are repeatedly executed, and when it is determined in step S180 that the start of the engine 22 has been completed (the cranking of the engine 22 has been completed), the maximum slope value ΔVafmax is determined using the starting voltage Vaf0. Is normalized to set the normalized maximum slope value ΔVafmaxno (step S190), and the set normalized normal slope value ΔVafmaxno is used to set the learning value ΔVafmaxlv of the responsiveness of the air-fuel ratio sensor 135a (step S200). ), This routine is terminated.

  In the embodiment, the normalized maximum slope value ΔVafmaxno in step S190 is set by using the maximum slope value ΔVafmax and the start voltage Vaf0 to set the air-fuel ratio sensor 135a corresponding to a predetermined air-fuel ratio (for example, theoretical air-fuel ratio) AFset. This is performed by normalizing (converting) the maximum slope value ΔVafmax in the predetermined air-fuel ratio corresponding voltage Vafset which is the output voltage Vaf. FIG. 7 is an explanatory diagram illustrating an example of a relationship line indicating a relationship between the starting voltage Vaf0 and the maximum slope value ΔVafmax. Hereinafter, the maximum slope value corresponding to each start time voltage Vaf0 in this relationship line is represented as “ΔVafmaxf [Vaf0]”. The relationship line is obtained by, for example, obtaining a plurality of relationships between the starting voltage Vaf0 and the maximum slope value ΔVafmax in advance by experiment or analysis, and plotting them as points, respectively, and performing function approximation by the least square method using the plotted points. It can be determined by doing. As can be seen from FIG. 7, the air-fuel ratio sensor 135a has a characteristic in which the maximum slope value ΔVafmax differs depending on the starting voltage Vaf0. Specifically, the starting voltage Vaf0 is maximized in the vicinity of the predetermined air-fuel ratio corresponding voltage Vafset. The maximum slope value ΔVafmax decreases as the distance from the vicinity of the air-fuel ratio corresponding voltage Vafset increases. In view of this, in the embodiment, the maximum slope value ΔVafmax, the start time voltage Vaf0 in the relationship line, the maximum slope values ΔVafmaxf [Vaf0] and ΔVafmaxf [Vafset] corresponding to the predetermined air-fuel ratio corresponding voltage Vafset are used. It is assumed that the maximum slope value ΔVafmaxmo after normalization is calculated by the equation (2). Such processing makes it easy to use the data (maximum normalized slope value ΔVafmaxmo). FIG. 7 also shows the above-mentioned predetermined voltage Vafref for reference. In the region where the starting voltage Vaf0 is equal to or higher than the predetermined voltage Vafref, the value of “ΔVafmaxf [Vafset] / ΔVafmaxf [Vaf0]” in the expression (2) becomes considerably large, and therefore the normalization accuracy (reliability) becomes relatively low. Conceivable. For this reason, in the embodiment, in the process of step S110 described above, a voltage condition in which the output voltage Vaf of the air-fuel ratio sensor 135a is less than the predetermined voltage Vafref is considered.

  ΔVafmaxno = ΔVafmax ・ ΔVafmaxf [Vafset] / ΔVafmaxf [Vaf0] (2)

  The responsiveness learning value ΔVafmaxlv of the air-fuel ratio sensor 135a in step S200 is set using the following equation (3) using the normalized maximum slope value ΔVafmaxmo and the previous learning value of responsiveness of the air-fuel ratio sensor 135a (previous ΔVafmaxlv). ). Here, in equation (3), “kv” is a reflection coefficient kv for reflecting the normalized maximum slope value ΔVafmaxmo to the new learning value ΔVafmaxlv, and is a value larger than the value 0 and smaller than the value 1, for example, Values 0.10, 0.15, 0.20, etc. can be used. Thus, by calculating the learning value ΔVafmaxlv of the responsiveness of the air-fuel ratio sensor 135a using the reflection coefficient kv, a sudden change in the learning value ΔVafmaxlv can be suppressed.

  ΔVafmaxlv = kv ・ ΔVafmaxmo ＋ (1-kv) ・ previous ΔVafmaxlv (3)

  Here, the reason why the responsiveness of the air-fuel ratio sensor 135a is learned during cranking of the engine 22 will be described. FIG. 8 is a diagram illustrating how the rotational speed Ne of the engine 22, the intake air amount Qa, the output voltage Vaf of the air-fuel ratio sensor 135a, and the slope value ΔVaf change with time when the engine 22 is cranked and started by the motor MG1. FIG. As shown in FIG. 8, when cranking of the engine 22 by the motor MG1 is started (time t11), the output voltage Vaf of the air-fuel ratio sensor 135a increases due to the increase in the rotational speed Ne of the engine 22 and the intake air amount Qa. (Becomes a lean value) and the slope value ΔVaf increases. At the time of cranking of the engine 22 (particularly, before the rotation speed Ne reaches the predetermined rotation speed Nest), fuel is not injected by the engine 22 and the intake air amount Qa is relatively small. Therefore, during operation in which fuel injection is performed by the engine 22, or when fuel injection is not performed by the engine 22, the intake air amount Qa is relatively large (the fuel while the engine 22 rotates at a relatively high rotational speed Ne). Compared to the time of fuel cut, a finer difference in the response of the air-fuel ratio sensor 135a tends to appear in the slope value ΔVaf. As a result, the responsiveness learning of the air-fuel ratio sensor 135a can be more appropriately learned by calculating the responsiveness learning value ΔVafmaxlv of the air-fuel ratio sensor 135a when the engine 22 is cranked. Further, the hybrid vehicle 20 travels while intermittently operating the engine 22 (while starting or stopping the engine 22) in a so-called one trip from the system start to the system stop. By learning the responsiveness of 135a, the learning is performed at more opportunities as compared with the case of learning the responsiveness of the air-fuel ratio sensor 135a after a certain amount of time has elapsed after the engine 22 is started. It is thought that you can.

  The operation when learning the responsiveness of the air-fuel ratio sensor 135a (updating the learned value ΔVafmaxlv) has been described. Next, the operation when permitting the start of the air-fuel ratio feedback control after the engine 22 is started using the responsiveness learning value ΔVafmaxlv of the air-fuel ratio sensor 135a will be described. FIG. 9 is a flowchart illustrating an example of an air-fuel ratio F / B control start permission routine executed by the engine ECU 24. This routine is started when the engine 22 is started.

  When the air-fuel ratio F / B control start permission routine is executed, the CPU 24a of the engine ECU 24 first inputs the learning value ΔVafmaxlv (step S300) and starts the air-fuel ratio feedback control based on the input learning value ΔVafmaxlv. A start air-fuel ratio AFst is set as an allowed air-fuel ratio (step S310). Here, in the embodiment, the relationship between the learning value ΔVafmaxlv and the starting air-fuel ratio AFst is determined in advance and stored in the ROM 24b as a starting air-fuel ratio setting map, and the starting air-fuel ratio AFst is mapped when the learning value ΔVafmaxlv is given. From this, the corresponding starting air-fuel ratio AFst is derived and set. An example of the start air-fuel ratio setting map is shown in FIG. As shown in the figure, the starting air-fuel ratio AFst is set to a fixed value AFst1 in a range where the learning value ΔVafmaxlv is equal to or larger than a predetermined value ΔVafmaxlv1 within a range (rich side) smaller than the target air-fuel ratio AF * (for example, the theoretical air-fuel ratio). In a region where the learning value ΔVafmaxlv is less than the predetermined value ΔVafmaxlv1, the smaller the learning value ΔVafmaxlv is set, the larger the tendency is. The reason for setting the start air-fuel ratio AFst in such a tendency will be described later.

  When the start air-fuel ratio AFst is set in this way, the detected air-fuel ratio AFdet corresponding to the output voltage Vaf of the air-fuel ratio sensor 135a is input (step S320), and a predetermined time Tref (for example, 400 msec, 500 msec, 600 msec, etc.) from the completion of the start of the engine 22 ) Has elapsed (step S330), and whether or not the detected air-fuel ratio AFdet is greater than or equal to the start air-fuel ratio AFst (step S340), and when the predetermined time Tref has not elapsed since the start of the engine 22 has been completed, When the detected air-fuel ratio AF is less than the start air-fuel ratio AFst, the process returns to step S320, and when the start of the engine 22 is completed or a predetermined time Tref has elapsed and the detected air-fuel ratio AFdet is equal to or greater than the start air-fuel ratio AFst. Allow the start of feedback control (step 350), and ends the present routine.

  FIG. 11 is an explanatory diagram showing an example of changes over time in the rotational speed Ne of the engine 22, the output voltage Vaf of the air-fuel ratio sensor 135a, the air-fuel ratio feedback correction amount ΔQf, and whether or not the air-fuel ratio feedback control is executed. In the figure, the solid line shows the state of the embodiment, and the alternate long and short dash line shows the state of the comparative example in which the air-fuel ratio feedback control is started at time t21 when the predetermined time Tref has elapsed since the start of the engine 22. In the example of FIG. 11, the state when the response of the air-fuel ratio sensor 135a is relatively low is shown. In addition, the actual air-fuel ratio (actual AF) normally swings relatively large toward the lean side when the engine 22 is started (during cranking), and after the engine 22 is started, once swings largely toward the rich side, It approaches the fuel ratio AF *. In the comparative example, since the air-fuel ratio feedback control is started at time t21, the air-fuel ratio feedback control is started in a state where the detected air-fuel ratio AFdet is somewhat away from the target air-fuel ratio AF *. ) May swing greatly toward the lean side with respect to the target air-fuel ratio AF *. In contrast, in the embodiment, when the detected air-fuel ratio AFdet is less than the start air-fuel ratio AFst at time t21, the air-fuel ratio feedback control is started at time t22 when the detected air-fuel ratio AFdet reaches or exceeds the start air-fuel ratio AFst. Thus, it is possible to suppress the actual air-fuel ratio (actual AF) from greatly swinging toward the lean side. When the air-fuel ratio sensor 135a has high responsiveness (for example, when the learned value ΔVafmaxlv is equal to or greater than the predetermined value ΔVafmaxlv1), the predetermined time Tref is set to the actual air-fuel ratio (actual AF) even if the air-fuel ratio feedback control is started. The time when it is considered that the air-fuel ratio AF * does not fluctuate greatly to the lean side is used. The start air-fuel ratio AFst starts air-fuel ratio feedback control in accordance with the responsiveness learning value ΔVafmaxlv of the air-fuel ratio sensor 135a (ease of deviation between the actual air-fuel ratio (actual AF) and the detected air-fuel ratio AFdet). Even if the actual air-fuel ratio (actual AF) does not fluctuate more lean than the target air-fuel ratio AF *, a value is set. Accordingly, by setting the start air-fuel ratio AFst according to the learning value ΔVafmaxlv, the air-fuel ratio feedback control can be started at a more appropriate timing. The timing at which the air-fuel ratio feedback control is started by setting the start air-fuel ratio AFst so that it becomes richer than the target air-fuel ratio AF * and the learning value ΔVafmaxlv becomes smaller (the tendency to approach the target air-fuel ratio AF *). Tends to be slower as the learning value ΔVafmaxlv is smaller.

  According to the hybrid vehicle 20 of the embodiment described above, the response of the air-fuel ratio sensor 135a is learned using the maximum slope value ΔVafmax based on the slope value ΔVaf of the output voltage Vaf of the air-fuel ratio sensor 135a when the engine 22 is cranked. Since the value ΔVafmaxlv is calculated, the response of the air-fuel ratio sensor 135a can be learned more appropriately and at a relatively large number of opportunities.

  In the hybrid vehicle 20 of the embodiment, the responsiveness of the air-fuel ratio sensor 135a is learned when the engine 22 is cranked. However, depending on the situation when the engine 22 is cranked, the responsiveness of the air-fuel ratio sensor 135a. It is good also as what does not learn. An example of the air-fuel ratio sensor responsiveness learning routine in this case is shown in FIG. This routine is the same as the air-fuel ratio sensor response learning routine of FIG. 6 except that the processing of steps S400 to S420 is added. Therefore, the same process is given the same step number, and the detailed description thereof is omitted.

  In the air-fuel ratio sensor responsiveness learning routine of FIG. 12, if it is determined in step S180 that the start of the engine 22 has been completed (the cranking of the engine 22 has been completed), the battery temperature Tb of the battery 50 and the engine by the motor MG1. 22 is input (step S400), and the battery temperature Tb of the battery 50 is set to the threshold value Tbref1, when the engine 22 makes one rotation after the cranking of 22 is started. In addition to comparing with Tbre2 (step S410), the determination rotational speed Ne of the engine 22 is compared with a threshold value Neref (step S420). Here, the battery temperature Tb of the battery 50 is input from the battery ECU 52 via the HVECU 70 as detected by the temperature sensor 51. Further, in the embodiment, the determination rotational speed Nej of the engine 22 is read and inputted based on the crank position from the crank position sensor 140.

  As described above, when the engine 22 is started, the cranking torque Tc is output from the motor MG1 within the range of the input / output limits Win and Wout of the battery 50, and the drive shaft 36 is output along with the output of the cranking torque Tc. The engine 22 is cranked by outputting a torque for canceling the acting torque from the motor MG2. When the battery temperature Tb is lower or higher than the appropriate temperature range, the output limit Wout of the battery 50 is relatively small. Therefore, the cranking torque Tc is relatively small, and the rise of the rotational speed Ne of the engine 22 is delayed. (The increase in the rotational speed Ne becomes moderate). The threshold values Tbref1 and Tbref2 and the threshold value Neref are used for determining whether or not such a situation exists. As the threshold value Tbref1, for example, a temperature slightly lower than the predetermined temperature Tblo (for example, 0 ° C., 5 ° C., 10 ° C., etc.) can be used. Further, as the threshold value Tbref2, for example, a temperature slightly higher than the predetermined temperature Tbhi (for example, 45 ° C., 50 ° C., 55 ° C., etc.) can be used. Furthermore, as the threshold value Neref, for example, 300 rpm, 400 rpm, 500 rpm, or the like can be used.

  When the battery temperature Tb is equal to or higher than the threshold value Tbref1 and equal to or lower than the threshold value Tbref2 and the determination speed Nej of the engine 22 is equal to or higher than the threshold value Neref, the maximum inclination value ΔVafmaxno is normalized and the normalized maximum inclination value ΔVafmaxno is set as in the embodiment. At the same time (step S190), the responsiveness learning value ΔVafmaxlv of the air-fuel ratio sensor 135a is set using the set normalized maximum slope value ΔVafmaxno (step S200), and this routine ends. In this case, the responsiveness of the air-fuel ratio sensor 135a is learned.

  On the other hand, when the battery temperature Tb is lower than the threshold value Tbref1 or higher than the threshold value Tbref2, and when the determination rotational speed Nej of the engine 22 is lower than the threshold value Neref, this routine is terminated without executing the processing of steps S190 and S200. . In this case, the response of the air-fuel ratio sensor 135a is not learned.

  When the cranking torque Tc is small and the rise of the rotational speed Ne of the engine 22 is slow (the increase in the rotational speed Ne is slow), the amount of exhaust from the engine 22 is small, and therefore, the lean side of the output voltage Vaf of the air-fuel ratio sensor 135a. The change to the value slows down, and the maximum slope value ΔVafmax decreases. For this reason, if the responsiveness of the air-fuel ratio sensor 135a is learned using the maximum slope value ΔVafmax at this time, the learned value ΔVafmaxlv may be likely to vary. In this modification, based on this, when the battery temperature Tb is lower than the threshold value Tbref1 or higher than the threshold value Tbref2, and when the determination rotational speed Nej of the engine 22 is lower than the threshold value Neref, the response of the air-fuel ratio sensor 135a is learned. It was decided not to do. Thereby, variation in the learning value ΔVafmaxlv can be suppressed.

  According to this modification, when the battery temperature Tb is lower than the threshold value Tbref1 or higher than the threshold value Tbref2, and when the engine speed for determination Nej is lower than the threshold value Neref, the response of the air-fuel ratio sensor 135a is not learned. Thus, the variation in the learning value ΔVafmaxlv can be suppressed.

  In this modification, it is determined whether or not to learn the responsiveness of the air-fuel ratio sensor 135a using the battery temperature Tb and the determination rotational speed Nej of the engine 22, but only one of them is used. It may be determined whether or not to learn the responsiveness of the air-fuel ratio sensor 135a.

  In this modification, when the battery temperature Tb is lower than the threshold value Tbref1 or higher than the threshold value Tbref2, the responsiveness of the air-fuel ratio sensor 135a is not learned, but instead of this, the cranking torque Tc ( When the torque set within the range of the output limit Wout of the battery 50 is limited to less than the threshold value Tcref, the response of the air-fuel ratio sensor 135a may not be learned. Here, as the threshold value Tcref, torque corresponding to the output limit Wout of the battery 50 when the battery temperature Tb is the threshold value Tbref1 or the threshold value Tbref2 can be used.

  Further, in this modified example, when the determination rotational speed Nej of the engine 22 (the rotational speed Ne of the engine 22 when the engine 22 makes one revolution after starting the cranking of the engine 22 by the motor MG1) is less than the threshold value Neref. However, instead of learning the responsiveness of the air-fuel ratio sensor 135a, the air-fuel ratio sensor is replaced when the increase speed (increase amount per unit time) ΔNe of the engine 22 is less than the threshold value ΔNeref. The learning of the responsiveness of the air-fuel ratio sensor 135a is not performed when the time tst required for the engine speed Ne to reach the threshold value Neref is longer than the threshold value tstref. You may do it. Here, as the threshold value ΔNref and the threshold value tstref, values corresponding to the threshold value Neref can be used, respectively.

  In the hybrid vehicle 20 of the embodiment, the maximum slope value ΔVafmax is normalized by using the starting voltage Vaf0 and the normalized maximum slope value ΔVafmaxno is set. However, instead of or in addition to the starting voltage Vaf0, the start is performed. The normalized maximum slope value ΔVafmaxno may be set by normalizing the maximum slope value ΔVafmax using one or more parameters other than the hour voltage Vaf0 (for example, the atmospheric pressure Pa, the throttle opening TH, the intake air temperature Tin, etc.). Good. An example of an air-fuel ratio sensor responsiveness learning routine in the case of normalizing the maximum slope value ΔVafmax using the atmospheric pressure Pa and the throttle opening TH instead of the starting voltage Vaf0 and setting the normalized maximum slope value ΔVafmaxno It is shown in FIG. This routine is the same as the air-fuel ratio sensor responsiveness learning routine of FIG. 6 except that the processes of steps S500 and S510 are executed instead of the process of step S190. Therefore, the same process is given the same step number, and the detailed description thereof is omitted.

  In the air-fuel ratio sensor responsiveness learning routine of FIG. 13, when it is determined in step S180 that the start of the engine 22 has been completed (the cranking of the engine 22 has been completed), it is detected by the atmospheric pressure sensor 89 and received from the HVECU 70. The atmospheric pressure Pa and the throttle opening TH from the throttle valve position sensor 146 are input (step S500), and the maximum inclination value ΔVafmax is normalized by using the input atmospheric pressure Pa and the throttle opening TH. The maximum post-slope value ΔVafmaxno is set (step S510), the learning value ΔVafmaxlv of the responsiveness of the air-fuel ratio sensor 135a is set using the set post-normalization maximum slope value ΔVafmaxno (step S200), and this routine is terminated. To do.

  In the embodiment, the normalized maximum slope value ΔVafmaxno in step S510 is set by using the maximum slope value ΔVafmax, the atmospheric pressure Pa and the throttle opening TH, a predetermined atmospheric pressure (for example, 1 atmospheric pressure) Path, and the predetermined opening. This is performed by normalizing (converting) the maximum inclination value ΔVafmax in THset (for example, the above-described basic opening THtmp). FIG. 14 is an explanatory diagram showing an example of a relationship line showing the relationship between the atmospheric pressure Pa and the maximum inclination value ΔVafmax, and FIG. 15 is an example of a relationship line showing the relationship between the throttle opening TH and the maximum inclination value ΔVafmax. It is explanatory drawing which shows. Hereinafter, the maximum inclination value corresponding to the atmospheric pressure Pa in the relationship line between the atmospheric pressure Pa and the maximum inclination value ΔVafmax is expressed as “ΔVafmaxf [Pa]”, and in the relationship line between the throttle opening TH and the maximum inclination value ΔVafmax. The maximum inclination value corresponding to the throttle opening TH is expressed as “ΔVafmaxf [TH]”. 14 and 15 can be obtained in the same manner as the relationship line in FIG. As can be seen from FIGS. 14 and 15, the air-fuel ratio sensor 135a has a characteristic in which the maximum inclination value ΔVafmax differs depending on the atmospheric pressure Pa and the throttle opening TH, specifically, the smaller the atmospheric pressure Pa, the smaller the throttle opening. The smaller the degree TH, the smaller the characteristic. Based on this, in this modified example, the correction coefficient obtained by dividing the maximum inclination value ΔVafmaxf [Paset] corresponding to the predetermined atmospheric pressure Paset in the relationship line in FIG. 14 by the maximum inclination value ΔVafmaxf [Pa] corresponding to the atmospheric pressure Pa. Kpa and a correction coefficient Kth obtained by dividing the maximum inclination value ΔVafmaxf [THset] corresponding to the predetermined opening THset in the relationship line of FIG. 15 by the maximum inclination value ΔVafmaxf [TH] corresponding to the throttle opening TH, The normalized maximum slope value ΔVafmaxmo is calculated by multiplying the maximum slope value ΔVafmax. By such processing, the data (maximum normalized slope value ΔVafmaxmo) can be easily used as in the embodiment.

  In the hybrid vehicle 20 of the embodiment, the maximum gradient value ΔVafmax at the time of cranking of the engine 22 is normalized to set the normalized maximum gradient value ΔVafmaxno, and the air-fuel ratio sensor 135a is set using the normalized maximum gradient value ΔVafmaxno. However, without normalizing the maximum slope value ΔVafmax, for example, the starting voltage Vaf0 and the maximum slope value ΔVafmax are associated with each other and set as a learned value ΔVafmaxlv [Vaf0]. May be.

  In the hybrid vehicle 20 of the embodiment, the learned value ΔVafmaxlv is obtained by the above equation (3) using the normalized maximum slope value ΔVafmaxmo, the previous learned value of the response of the air-fuel ratio sensor 135a (previous ΔVafmaxlv), and the reflection coefficient kv. However, the maximum slope value ΔVafmaxmo after normalization may be set to the learning value ΔVafmaxlv as it is.

  In the hybrid vehicle 20 of the embodiment, the responsiveness learning value ΔVafmaxlv of the air-fuel ratio sensor 135a is used for setting the start timing of the air-fuel ratio feedback control. In addition to or instead of this, for example, air-fuel ratio feedback It may be used for setting the correction amount ΔQf (for example, setting of the proportional term gain k1 and the integral term gain k2, the setting of the limit value used for limiting the proportional term and the integral term, etc.).

  In the hybrid vehicle 20 of the embodiment, the air-fuel ratio feedback correction amount ΔQf used for setting the target fuel injection amount Qf * is the detected air-fuel ratio AFdet that is the air-fuel ratio corresponding to the output voltage Vaf of the air-fuel ratio sensor 135a and the target air-fuel ratio AF. * Is used to calculate by the above formula (1), but as shown in the following formula (4), the integral term in formula (1) is limited by the limit values ΔQflim and −ΔQflim. It is good. In this case, the limit value ΔQflim is obtained by applying the learned value ΔVafmaxlv to the integral term limit value setting map illustrated in FIG. 16 in which the relationship between the learned value ΔVafmaxlv of the responsiveness of the air-fuel ratio sensor 135a and the limit value ΔQflim is predetermined. It may be set. In the example of FIG. 16, the limit value ΔQflim is set so as to decrease as the learning value ΔVafmaxlv decreases. When the responsiveness of the air-fuel ratio sensor 135a is low, the detected air-fuel ratio AFdet tends to deviate from the target air-fuel ratio AF * as compared to when the responsiveness is high, and the magnitude of the integral term in the equation (1) and thus the air-fuel ratio Although it is considered that the magnitude of the feedback correction amount ΔQf tends to increase, the air-fuel ratio feedback correction amount is limited by limiting the integral term in Equation (1) using the limit value ΔQflim set to decrease as the learning value ΔVafmaxlv decreases. By using ΔQf for setting, it is possible to suppress the magnitude of the integral term in equation (1), and thus the magnitude of the air-fuel ratio feedback correction amount ΔQf, from becoming excessively large.

  ΔQf = k1 ・ (AF * -AF) + max (min (k2 ・ ∫ (AF * -AF) dt, ΔQflim),-ΔQflim) (4)

  In the hybrid vehicle 20 of the embodiment, the power from the motor MG2 is output to the drive shaft 36. However, as illustrated in the hybrid vehicle 120 of the modified example of FIG. 17, the drive shaft 36 transmits the power from the motor MG2. It may be connected to an axle (an axle connected to the wheels 39a and 39b in FIG. 17) different from the connected axle (the axle to which the drive wheels 38a and 38b are connected).

  In the hybrid vehicle 20 of the embodiment, the power from the engine 22 is output to the drive shaft 36 connected to the drive wheels 38a and 38b via the planetary gear 30, but is exemplified in the hybrid vehicle 220 of the modification of FIG. As described above, the inner rotor 232 connected to the crankshaft of the engine 22 and the outer rotor 234 connected to the drive shaft 36 that outputs power to the drive wheels 38a and 38b have a part of the power from the engine 22. A counter-rotor motor 230 that transmits power to the drive shaft 36 and converts remaining power into electric power may be provided.

  In the hybrid vehicle 20 of the embodiment, the power from the engine 22 is output to the drive shaft 36 connected to the drive wheels 38a and 38b via the planetary gear 30, and the power from the motor MG2 is output to the drive shaft 36. However, as illustrated in the hybrid vehicle 320 of the modification of FIG. 19, the motor MG is attached to the drive shaft 36 connected to the drive wheels 38a and 38b via the transmission 330 and the clutch 329 is attached to the rotation shaft of the motor MG. The power from the engine 22 is output to the drive shaft 36 via the rotation shaft of the motor MG and the transmission 330, and the power from the motor MG is output to the drive shaft via the transmission 330. It is good also as what outputs to. Alternatively, as illustrated in the hybrid vehicle 420 of the modified example of FIG. 20, the power from the engine 22 is output to the drive shaft 36 connected to the drive wheels 38 a and 38 b via the transmission 430 and the power from the motor MG. May be output to an axle different from the axle to which the drive wheels 38a, 38b are connected (the axle connected to the wheels 39a, 39b in FIG. 20). In other words, any type of hybrid vehicle may be used as long as it includes an engine and an electric motor that inputs and outputs driving power.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the engine 22 corresponds to the “engine”, the motor MG1 corresponds to the “motor”, the battery 50 corresponds to the “battery”, and the output voltage Vaf of the air-fuel ratio sensor 135a when the engine 22 is cranked. The engine ECU 24 that executes the air / fuel ratio sensor responsiveness learning routine of FIG. 6 for calculating the responsiveness learned value ΔVafmaxlv of the air / fuel ratio sensor 135a using the maximum inclination value ΔVafmax based on the inclination value ΔVaf corresponds to the “control device”.

  Here, the “engine” is not limited to the engine 22 that outputs power using gasoline or light oil as a fuel, and may be any type of engine such as a hydrogen engine. The “motor” is not limited to the motor MG1 configured as a synchronous generator motor, and may be any type of motor that can crank the engine, such as an induction motor. The “battery” is not limited to the battery 50 configured as a lithium ion secondary battery, but can exchange power with the motor, such as a nickel hydride secondary battery, a nickel cadmium secondary battery, and a lead storage battery. Any type of battery may be used. As the “control device”, a learning value ΔVafmaxlv of the responsiveness of the air-fuel ratio sensor 135a is calculated using a maximum inclination value ΔVafmax based on the inclination value ΔVaf of the output voltage Vaf of the air-fuel ratio sensor 135a when the engine 22 is cranked. The present invention is not limited to this, and any method may be used as long as the response of the air-fuel ratio sensor is learned by using the gradient of the output value of the air-fuel ratio sensor when the engine is cranked by the motor.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of control devices for hybrid vehicles.

  20, 120, 220, 320, 420 Hybrid vehicle, 22 engine, 24 electronic control unit for engine (engine ECU), 26 crankshaft, 30 planetary gear, 36 drive shaft, 37 differential gear, 38a, 38b drive wheel, 39a, 39b Wheel, 40 Motor electronic control unit (motor ECU), 41, 42 Inverter, 43, 44 Rotation position detection sensor, 50 battery, 51 Temperature sensor, 52 Battery electronic control unit (battery ECU), 70 Hybrid electronic control unit (HV ECU), 72 CPU, 74 ROM, 76 RAM, 80 power switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 Rake pedal, 86 Brake pedal position sensor, 88 Vehicle speed sensor, 89 Atmospheric pressure sensor, 122 Air cleaner, 124 Throttle valve, 126 Fuel injection valve, 128 Intake valve, 130 Spark plug, 132 Piston, 134 Purification device, 134a Purification catalyst, 134b Temperature Sensor, 135a Air-fuel ratio sensor, 135b Oxygen sensor, 136, Throttle motor, 138 Ignition coil, 140 Crank position sensor, 142 Water temperature sensor, 143 Pressure sensor, 144 Cam position sensor, 146 Throttle valve position sensor, 148 Air flow meter, 149 Temperature Sensor, 150 variable valve timing mechanism, 230 pair rotor motor, 232 inner rotor, 234 outer rotor, 329 Clutch, 330, 430 Transmission, MG, MG1, MG2 motor.

Claims (6)

An engine; a motor capable of cranking the engine; a battery capable of supplying electric power to the motor; and an air-fuel ratio sensor attached to an exhaust system of the engine and having an output value that varies depending on the air-fuel ratio. A control device for a hybrid vehicle,
Learning the responsiveness of the air-fuel ratio sensor using the slope of the output value of the air-fuel ratio sensor during cranking of the engine by the motor.
The control apparatus of the hybrid vehicle characterized by the above-mentioned. A control device for a hybrid vehicle according to claim 1,
The cranking maximum slope value, which is the maximum value of the slope of the output value of the air-fuel ratio sensor at the time of cranking of the engine, is the output value of the air-fuel ratio sensor at the start of cranking of the engine, the atmospheric pressure, and the throttle opening. Normalizing using at least one of the degrees, and calculating a learning value of the responsiveness of the air-fuel ratio sensor using the cranking maximum slope value after the normalization,
Control device for hybrid vehicles. A control device for a hybrid vehicle according to claim 2,
Subtract the reflection coefficient from the value 1 to the value obtained by multiplying the calculated maximum gradient value after cranking by the reflection coefficient larger than the value 0 and smaller than the value 1, and the previous learning value of the responsiveness of the air-fuel ratio sensor. The sum of the value multiplied by the value is calculated as a learning value for the responsiveness of the air-fuel ratio sensor.
Control device for hybrid vehicles. A control device for a hybrid vehicle according to any one of claims 1 to 3,
When the output of the motor is limited to less than a threshold value or when the rise of the engine speed during cranking of the engine is slower than the threshold value, the response of the air-fuel ratio sensor is not learned.
Control device for hybrid vehicles. A control apparatus for a hybrid vehicle according to any one of claims 1 to 4,
After starting the engine, the timing for starting the air-fuel ratio feedback control is set so as to be delayed as the responsiveness of the air-fuel ratio sensor is lower.
Control device for hybrid vehicles. A hybrid vehicle control device according to any one of claims 1 to 5, comprising:
The limit value of the integral term in the air-fuel ratio feedback control is set so as to decrease as the responsiveness of the air-fuel ratio sensor decreases.
Control device for hybrid vehicles.

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